Electronic devices are typically designed to operate in specific ambient conditions, defined typically by allowable humidity and temperature ranges, which are typically normal for a given geographical area in which the device is supposed to operate. For example, a device may be supposed to operate in a range of temperatures from +5 to +35 degrees C. This range is typically normal for interior of households.
However, at end-user premises, a device may be, usually unintentionally, is placed in an environment where the conditions exceed the allowed temperature range. For example, a DVD player or a set-top box may be placed in a closed cabinet which is subject to sunshine. In those conditions, taking into account the heat generated by the device itself and the heat of the sunshine, the ambient atmosphere of the device will likely exceed the allowed temperature. This may lead to failure of the device due to overheating. Moreover, the device may overheat even if the ambient temperature is within allowed limits, but the device is installed improperly, e.g. when the ventilation openings at the device casing are covered, causing increase of thermal resistance of the device, e.g. by laying a newspaper on top of the device.
It is, therefore desirable to monitor the ambient temperature for the electronic device in order e.g, to cause its automatic power-down or to store data for servicing purposes, when the temperature exceeds allowed range. It is further desirable to monitor the change of thermal resistance of the electronic device.
For example, U.S. Pat. No. 8,374,730 presents methods and apparatuses for dynamically budgeting power usage to control temperatures in a data processing system. The system includes a first sensor to determine an ambient temperature of an environment in which the data processing system is; a controller coupled to the sensor to control operations of the data processing system according to the ambient temperature; and a second sensor to determine an actual temperature of a component of the data processing system.
Similarly, U.S. Pat. No. 6,754,607 presents a failure diagnosis method for control apparatus, the apparatus comprising a first sensor for detecting the internal temperature of the control apparatus, a second sensor for detecting the external temperature of the control apparatus, and internal memory media for storing information that has been created inside the control apparatus.
Such dedicated ambient temperature sensors add to the cost and is complexity of the device.